How do you handle this?

Practice this in training.  I deal with this some days in training.  I chalk them up to mental toughness days and push through and then when those bad thoughts creep in during a race, I can think back on the training and know they will go away.

Here, I have a suggestion for you. Try this:

HTFU

 

That is all

Edited by zed707 2009-06-15 5:24 PM

Is it at a consistent point in the bike/run; like right after the start or the halfway point, etc.? That may provide some insight into why it is happening and what you can do to head it off. Oh yeah, and caffeine helps

I thought about this on my ride yesterday...was 2/3 rds of the way up my second hill set (roughly 2k foot climb), my legs were burning, my heart was thumping and I just thought...I could just turn around at the next intersection, cruise down to that cross street and take it all the way back to my car going downhill...

but then I remember my new Tri Club team mates waiting at the top with a table full of food (snickers, granola, C-Milk, mike and Ikes, Gummy Bears, Pretzels etc...) and so I finished it off. Felt great at the top and a snickers never tasted soooo good.

If I could run that fast I'd be ok with that feeling.

I dont run that fast but it does my 7 min miles to 8.5 or my bike MPH from 21 to 16. ussally passing some one helps me get out of it

PLMsbr
 it ussally comes right after the midpoint of one the bike or run. it seems to be worse the better I feel I am doing in the first half

Interesting, especially the part about being worse if the first half went well. By doing well, let me assume you mean that you have a good time (and correct me if I'm wrong). That usually also means you are working very hard, so maybe you are realizing that you still have to keep up that level of effort (and suffering) for the second half of the bike/run... which can be a very intimidating thought. I once heard Siri Lindley talk about the mental barriers that we all have that prevent us from doing what we are capable of. Because once we realize we *can* do it, then we no longer have the excuse that we can't. We know it will hurt, but we know it is possible.

You say this is happening in races, but I have a feeling that it happens in training as well; maybe you just don't notice it as much. Try and look for this feeling when you are training (e.g. "I'm a little tired, I'll just relax for a couple minutes and then get back to it"). The better you can recognize and deal with that feeling in training, the better you'll be prepared to see it coming in a race and push through it.

PLMsbr - funny is it does not happen in training maybe cause I rarley time my training sessions. In training I push to a certain heart rate or feeling and when I feel a bad effort I just kick it up a notch 

giggles, my thoughts exactly!
biking 24mph and running 12mph?  schweet!